Caption: Light microscopy of human normal large bowel mucosa. The mucosa consists of a surface epithelial cell layer formed into long straight glands (crypts of Lieberkuhn) that greatly increase the surface area for cell absorption and secretion. Macroscopically the mucosa may show folds as seen here due to local muscle contraction. The glands absorb fluid from the waste (fecal) material and secrete mucus to lubricate its passage through the bowel. Magnification x35 when narrow width printed at 10 cm.